A pressing board assembly 60 of a conventional manual paper cutter is disclosed in FIG. 4, and generally includes a threaded rod 61 which is operated by rotating a wheel 62 connected to on end thereof and two guide members 64 each have a rack portion which are engaged with the threads of the threaded rod 61. The two guide members 64 are pivotably connected to two first links 63 respectively and the two first links 63 are pivotably connected to two respective first ends of two second links 65. The two respective second ends of the two second links 65 are pivotably connected to a pressing board 66. Two ends of the pressing board 66 are movably retained between two guide boards 67. By rotating the wheel 62, the pressing board 66 is lowered to press onto a pile of paper (not shown) and a cutting mechanism is activated to cut the pile of paper. It takes a lot of time to lower or to lift the pressing board 66 by rotating the wheel 62.
FIGS. 5 and 6 show an operation mechanism 70 for an electric paper cutter wherein the threaded rod 700 is connected to a first belt wheel 71 and a belt 72 reeves between the first belt wheel 71 and the second belt wheel 74 connected to an end of a driving rod 75 which is driven by a motor 73. The threaded rod 700 are engaged with two rack members which are respectively and pivotably connected to two first links 76. The two first links 76 are pivotably connected to two respective first ends of two second links. The two respective second ends of the two second links are pivotably connected to a pressing board 77. When activating the motor 73, the first and second belt wheels 71, 74 are rotated by the belt 72 so that the threaded rod 700 is rotated to activate the rack members, first links 76 and the second links to lower or lift the pressing board 77. Nevertheless, the user has to carefully calculate the time of the operation of the motor 73 so that the motor 73 will not overdrive after the pressing board 77 presses on the pile of paper.
The present invention intends to provide an operation mechanism for operation of pressing board of an electric paper cutter wherein the travel of the pressing board is controlled by sensors which send commands to stop the motor when the pressing board presses on the pile of paper.